Photomechanical process of producing finished and plastic casts.



'UNITED STATES Patented May 5, 1903.

f PATENT OFFICE.

CARL PIETZNEE, or VIENNA, AUSTRIA-HUNGARY.

PHOTOIVIECHANICAL PROCESS OF PRODUCING FINISHED AND PLASTIC CASTS.

SPECIFICATION forming partof Letters Patent No. 727,435, dated May 5, 1903. Application led-Augnst 18, 1899. Serial No. 727,710. `-(No specimens.)

To a/ZZ whom, t may concern:

Beit known that I, CARL PIETZNEE, imperial and royal court and chamber photographer, of 3 Mariahilferstrasse,Vienna VL in the Empire of Austria-Hungary, have invented a certain new and useful Improved Photomechanical Process for the Productionof Finished and Plastic Casts, of which the following is a specification.

The action of light on chromatic layers of glue is well known. The methods hitherto used for producing plastic models by means of such chromatic layers of glue have yielded only. very imperfect results-thatis to say, the reliefs thus obtained can only'be designated as surface reliefs,which are'of no use for utilization as plastic objects.

The new method which is the subject of the present invention yields in comparison with the above-characterized older method more perfect models, which render faithfully the artistic idea, and the individual peculiarity of the photographic original and the plastic features of it are so pronounced that their use as reliefs or with the aid of the usual mounting or casting methods as models, duc., is rendered possible in the most various branches of industry.

The present new method, as characterized regarding its results, is carried out normally in the following manner:

Approximately equal parts of agar-agar and pure gelatin are used and dissolved in as much water as is just necessary for dissolving both kinds of glue-that is to say, for the formation of a consistent mass of the same. After this mass `has been mixed with three to eight per cent. chromate-of-potash solution to sensitize it in accordance with the lightand-shade effects of the figure (or body) original to be photographed it is poured in as thick a layer as possible on entirely level glass plates and then dried while the light is excluded. The plates prepared in this manner are then ready for producing the models in relief, as described hereinafter, and they are especially adapted for the purpose, because they yield-a high relief capable of much resisting strength, and they are brought for the development of the latter first into lukewarm water, thereafter into warm water, and fin ally into water saturated with acetic acid.

In the accompanying drawings, Figure 1 is a sectional View of a'positive swelled relief; Fig. 2, Na similar view of a plastic cast therefrom. Fig. 3 is a negative swelled relief. Fig. 4 is. a sectional view of a positive cast taken from the relief of Fig. 3. Figs. 5 and 6 are sectional views illustrating the operation.

By means of a negative picture made in any ordinary manner a positive swelled re lief l, Fig. l, is obtained,.and from this a plaster cast 2, Fig. 2, isftaken, which results negative, of course, and which will be designated hereinafter as a"plastic matrix. By means of a diapositive-picture made from the same original a swelled relief' 3, Fig. 3, is produced, which will be negative. From this swelled relief a plastic cast 4 is taken, which results positive, Fig. 4, and which will be designated hereinafter as plastic counter-mold. Now a thin layer 5, of clay or some other plastic mass, is pressed into the plastic matrix 2, Fig. 5. The plastic countermold 4, Fig. 4, is then modeled over 'or corrected without regard to perfect resemblance or fine detail Vfeatures of the original, but with strict observance of the rules of plastic art, raising the places which are too deep by laying on some material, preferably wax or some other consistent plastic substance,while the placeswhich become too high are deepened by scraping. (Fig. 4 shows in full outlines the plastic counter-mold corrected in this manner.) On the plastic counter-mold which has thus been retouched (Fig. 4) in its general features, the clay impression 5, made by means of the plastic matrix, is now laid, and with Vthe aid of slight pressure the right form of height is given to it. This may also be effected in such a manner that the retouched plastic counter-mold 4, Fig. 4, is pressed from behind into the clay impression, which'is stillin the matrix, Fig. 5, and that the clay impression is lifted Vout with the plastic counter-moldand pressed 'on further, if necessary. In the clay impression which has thus been transferred to the plastic counter-mold parts which might have turned out too deep from the swelled relief cannot recede, but they must maintain themselves in their correct position in accordance I with the corrected plastic of the underlying IOO ing one negative cast from the positive relief and one positive cast from the negative relief correcting the positive cast taking a thin stamp from the uncorrected cast, applying the same to the corrected cast and applying slight pressure to said stamp to give it the right form substantially as described.

In Witness whereof I have hereunto set my hand in presence of two Witnesses.

CARL PIETZNER.

Witnesses:

ALvEsTo S. HoeUE, Y AUGUST FUGGER. 

